This whole business of full range vs. not has many factors which play into the choice. Clearly, the designers of Procella speakers are exceptionally well versed in movie sound track presentation and speaker design … the product speaks for itself.
Large room (and auditoria) and small room acoustics are radically different with respect to the problems, issues, and solutions each present and require. Mode 0 and modal density in large rooms is significantly different than in small rooms. How do you get a 100’ wide sound stage in a 15’ wide room? In a small room, how do you keep the delta in SPL in multiple rows of seats similar? In auditoria, how do you keep FR in the middle of the room equivalent to FR in the fourth row? Getting smooth, or at least consistent bass response in all the seating locations is a significant challenge and sucking up low frequencies isn’t necessarily the better choice.
So, let’s look at just a tiny portion of some of the issues. One of these are notches (very narrow band frequency cancellations). For the sake of this ramble, let’s assume a traditional 80Hz crossover between subs and mains. The notch frequency(ies) will be that frequency whose ¼ wave length is equal to the distance from the face of the speaker to the wall behind the speaker. For example, if your center channel speaker is 1’ from the back wall, you can expect a notch in the frequency response at 281Hz. What’s one way to get rid of the notch? If your crossover is set to 80Hz, move that center channel speaker more than 3.5’ away from that wall. The crossover frequency has a ¼ wavelength of 3.5’. Moving the speaker more than 3.5’ from that front wall lowers the notch frequency below 80Hz. With the notch frequency below the frequency being produced by the speaker … no notch. It’s not that simple, of course. The crossover is not a brick wall! You’d want the notch frequency(ies) low enough to not create an audible problem.
What happens when you push your sub(s) closer than 3.5’ from that front wall? The notch frequency is then higher than the highest frequency being produced by the subwoofer (or LF driver). It would be really nice if it were all that simple … music and speech is dynamic (test tones are not), we have a wall behind a speaker, walls to the sides of the speakers, a floor below and a ceiling above. Then we inject into the whole mess, the baffle wall (which, like any approach, is a solution to one set of issues while creating another).
If we push that sub against a wall, we’ve eliminated potential notch problems and provided boundary gain to help an under performing sub; but, we’ve also exacerbated modal response problems. We’ve placed the sub into a position which will increase the energy feeding modal frequencies. So now, we enter into the world of multiple subs (referring to the separate work of Todd Welti and Gerry Lemay). As subs are added, two things happen: (1) the modal ‘production’ of each sub can be utilized to provide constructive and destructive interference of the modes in the room (Welti’s work clearly states that in the four sub scenario, good bass response does not result in the listening positions rather that “consistent” bass response is created in the listening positions); and, (2) from Lemay’s work we discover that multiple subs in a room perform almost exactly as would a single sub placed at the acoustic midpoint between subs. (What you’re really attempting to do with placement is to organize the acoustic center of your low frequency drivers to be located in a “moderate” modal area.)
This leads (in small rooms) to the scenario where the ideal placement for the L/C/R speakers for the best sound stage, clarity, SPL delta between seats/rows, etc. is most likely exactly the wrong location to place low frequency drivers for the purpose of best low frequency response in the seating area (remember, we really don’t give a hoot about sound quality where people don’t sit). An advantage of the “sub sat” arrangement is to have the positional flexibility to meet the conflicting positional requirements of high/mid frequency drivers and the low frequency drivers.
Now here is the back side of all of this. Regardless of where your room/speaker dictates speaker placement, neither your subs nor your mains can be under performing anywhere within the cross over frequency range. That will muck up everything really, really quickly. The last thing you want is a massive, over performing sub and weak LCR's or vice versa. In the absence of skill and very good DSP processing, the impact in the cross over region is going to be very unpleasant and very much outside what was intended.*
In the end, what has to be achieved is to make your small room exhibit exactly the same acoustic performance of the much larger SMPTE or Academy reference rooms. That is a very tall order and, in the design and calibration of any space, all options need to be left on the table. As well, among the considerations is exactly who is going to perform the audio calibration (including treatment planning) and what tools, or devices, you’ll have available within your electronic configuration to perform the calibration. Someone with the knowledge, experience and proper tools can tackle problems and issues which could very easily frustrate, or be missed by, the most book learned DIYer on the planet.
Where Chuck and I differ is my statement would be "if you want a home system that matches the sound in the dubbing stage where the film was mixed, you have to duplicate that acoustic environment". When you go from a large room to a small room, the challenges are great (and clearly, your speaker kit has to be up to the task).
…and, yes, this is all very much an oversimplification and no, I’m not going to get down in the weeds here.
*Many consumer subs are at the optimal performance in the 35 to 40Hz area. To resolve this problem, you could add something like the P18 to your existing kit, and cross the P18 over with your existing sub at, say 40Hz. Getting a good set of subs/mains in the first place is certainly a better choice. Just because you have a pick'em up truck and an outhouse, doesn't mean you have a camper.